NFLDraftScout.com has four strong cornerback prospects rated as potential first-round picks, and LSU's Morris Claiborne remains at the top of the position as none of the elite prospects particularly stood out during testing drills at the Scouting Combine on Tuesday.

North Alabama's Janoris Jenkins is hovering around the top 10, and ran an impressive 4.46-second 40-yard dash, compared to Claiborne's 4.50. Alabama's 'Dre Kirkpatrick posted a 4.51, while Nebraska's Alfonzo Dennard ran a 4.55. All were very respectable times. (Combine 40 Times)

Dennard flipped the script a bit with an impressive 37-inch vertical jump, while Kirkpatrick (37), Claiborne (34.5) and Jenkins (33.5) lagged behind him a bit.

While Claiborne said he believes his speed helps separate him from the other top cornerbacks, he pointed to technique when asked to describe his game.

"More of a technician, and trying to funnel the guys instead of getting real physical with them at the line all the time," said Claiborne, who considers himself a better man coverage corner than zone.

The biggest mover of the day was clearly Central Florida's Josh Robinson, who torched the 40 in 4.33 seconds. He also led the defensive backs with a 133-inch broad jump and finished second in the position group with a 38 1/2-inch vertical. Currently projected as a fourth-round pick, Robinson figures to ride the wave up the draft board a bit leading into the pro day season.

Tackling machine. Great instincts. Field general. Luke Kuechly already had all the buzz words typically attributed to the top inside linebacker prospect in every draft.

But few people touted his outstanding athleticism - until Monday, when the former Boston College standout ran a blistering 4.50 unofficial 40, which would tie Robert McCune for the top time since 2000 by an inside linebacker. (40-yard dash results). He also led the inside linebackers with a 38-inch vertical jump.

The "official" 40 time will likely be adjusted down a bit, but that won't affect the bottom line. With that type of speed, and noted instincts in coverage, Kuechly has shown the ability to be a three-down linebacker in the NFL who can hold his own in coverage against running backs and the growing list of freakishly athletic tight ends.

That's exactly while Kuechly is a virtual lock for the first round despite playing at a position that has lot a lot of draft value in recent years. A source told NFLDraftScout.com last week that Kuechly, who posted 532 tackles in just three college seasons, might be the "safest" player in this draft.

UPDATE: We've noted several times during the Combine that none of the 40 times are technically official, and Kuechly finished the day with four different 40 clockings. His second run was clocked in 4.78 by a handheld time after he appeared to get a slow start. He was then asked to run a third time, which was timed at 4.59. So what time is he now listed with? 4.58. At the end of the day, throw out the 4.78 and know that Kuechly runs in the 4.5-4.6 range, which serve the purpose of proving his athleticism.

Several of the more highly regarded wide receivers of the 2012 draft may see their stock slip after running signficantly slower than expected Sunday at the Scouting Combine.

Baylor wideout Kendall Wright, who some regard as the draft's top talent at the position due to his ability to make the big play, clocked in at just 4.61 seconds, according to NFL.com. Wright had been projected to run in the 4.4s or better.

Wright was far from the only highly regarded receiver to produce a disappointing time in the 40-yard dash, however. LSU's Rueben Randle (4.55), Rutgers' Mohamed Sanu (4.67) and Arkansas' Joe Adams (4.55) also could force scouts to go back to the tape after running slower than anticipated.

These results come on the heels of a disappointing workout from NFLDraftScout.com's top-rated receiver, Oklahoma State junior Justin Blackmon. Blackmon elected not to run at the Combine citing a tight hamstring. He did perform in the positional drills, however, but appeared hesitant to run and cut with the aggression that characterized his spectacular career with the Cowboys.

For those arguing that Baylor quarterback Robert Griffin IIIshould leap Andrew Luck as the top quarterback -- and prospect -- of the 2012 draft, he helped the cause by demonstrating his unbelievable straight-line speed Sunday morning.

Griffin was unofficially clocked at 4.41 seconds by The NFL Network on his first attempt and ran even faster the second time around, zipping down the line at 4.38 seconds, according to the league's stopwatch.

The demonstration of spectacular speed was not a surprise considering Griffin's Olympic potential, but it nonetheless gives scouts an actual time to go with all of the Heisman winner's highlights.

NFL.com is reporting 40-yard dash times from the Combine, first an "unofficial" handheld time and later an "official" time provided from National Football Scouting.

NFLDraftScout.com explained the 40-yard dash timing process, along with verified all-time Combine records. Those who participate in the 40 actually run twice, and on each run they are timed by two hand-held stopwatches and one electronic timer (that is actually initiated by hand on the player's first movement). Combine data put together for NFL teams by National Scouting includes all six of those times for each player, but no single official time, but that information isn't typically known for a week or two following the conclusion of the Combine.

Of note: of the 36 offensive linemen NDS noted unofficial and official times for, 33 had slower times in the official listing, three were the same and none were listed as faster than their unofficial timing. Sixteen players had an official time at least a tenth of a second slower than their official time, led by Georgia's Cordy Glenn, who dropped 0.19 seconds from a blistering 4.96 for a 345-pound man to 5.15.

40-yard Dash ResultsCheck back here for updating results throughout the Combine. All times are unofficial.N/A = Prospects who haven't run or have chosen not to run

It is easy to be confused by the wide range of times being reported for players' 40-yard dash times. LSU's Trindon Holliday, for example, had been reported by some as having been timed as low as 4.22 seconds and as high as 4.34 seconds. Obviously a pretty significant disparity.

It's important to understand what happens to get the 40 times at the combine:

. Those who participate in the 40 actually run twice, and on each run they are timed by two hand-held stopwatches and one electronic timer (that is actually initiated by hand on the player's first movement.

. Combine data put together for NFL teams by National Scouting includes all six of those times for each player, but no single official time.

Team scouts and coaches have various approaches for getting the 40 time they use from those six timings. Some use averages. Some throw out slowest and fastest and then average the rest. Some ignore the whole thing and use a time taken by their own scout.

However, beware any 40-yard time that is labeled as "official" from the combine. In deference to the players, NFLDraftScout.com uses the best verifiable -- or listed -- time from the combine unless it is conspicuously skewed from the other times, which happens when a hand timer has an itchy trigger finger on the stopwatch. However, the times are usually well grouped.

Oregon junior cornerback Jairus Byrd was unable to workout at the Combine due to a groin pull, but struggled to reward scouts for their patience in testing in the mid to upper 4.6s in the 40-yard dash, according to scouts in attendance.

The time is certainly a concern for scouts, though they were also quick to point out that Byrd tested very well in shuttle drills (4.10 short shuttle, 6.75 3-cone). Each of these marks would have ranked among the top ten cornerbacks tested in Indianapolis and are indicative of the rare agility and burst Byrd showed throughout his career with the Oregon Ducks. If Byrd's name is familiar, it is because his father, Gill Byrd, was a long-time standout for the San Diego Chargers at cornerback.

A few hundred miles south, Hawaii cornerback Ryan Mouton suffered the same fate at his Pro Day today (held at the Home Depot Center in Los Angeles) that limited him at the Combine over a month ago -- a pulled hamstring. Still, the 5'09, 187 pound cornerback flashed some eye-popping explosion by dropping his 40-yard dash time from 4.51 seconds at the Combine to 4.46 seconds Thursday. So why did five-hundredths of a second rate as a significant improvement? Because Mouton, according to scouts in attendance, pulled up with the hamstring at about the 30 yard mark in the event and still posted a 4.46 second time. Had the injury not occurred, he likely would have been in the low to mid 4.3s... Mouton's explosiveness was on display in the broad jump, where he leapt 11'0 -- a mark beaten only by potential first round pick Darius Butler (Connecticut) among the cornerbacks tested at the Combine.

Northern Illinois defensive end/outside linebacker didn't necessarily have to workout for scouts Friday. The two-time MAC defensive player of the year was impressive off the edge at the Senior Bowl and flashed athleticism in Combine workouts, as well.

However, considering that many teams wanted to see him shed some time off his 40-yard dash, the move was a good one. English's fastest time at the Combine was 4.82 seconds, but he was clocked in the high 4.6s to low 4.7s according to scouts in attendance Friday, and was better in both defensive line and linebacker drills, as well.

The knock on English is that while he has good burst off the snap and reasonable straight-line speed, he doesn't necessarily change directions as fluidly as some teams operating the 3-4 defense would prefer out of their linebackers. In a 4-3 scheme, English, 6-2, 255 pounds, is probably best suited as an undersized defensive end, which is why many of the teams who had scouts on campus were from clubs operating out of the 3-4.

English has the tools to warrant consideration late in the first round, but this year's unique collection of outside linebackers and hybrid defensive ends likely to make the transition to the OLB position could push him into the mid second range. He is among a group of about a baker's dozen hybrid pass rushers (Brian Orakpo, Everette Brown, Brian Cushing, Aaron Maybin, Robert Ayers, Connor Barwin, Clay Matthews Jr, Clint Sintim, Paul Kruger, Michael Johnson, Lawrence Sidbury, Jr, Cody Brown, Zach Follett, etc.) scouts feel warrant first day consideration.